Cathode-ray oscillograph



July' l, 1.930. o. ACKERMANN curious an oscILpoGRAPH Filed June 22, 1929 x u n INVENTOR 0//0 /ca/ermd/m AT'TOFNEY Patented July l, 1930 sy MTI-:Nr oFFic-E OTTO ACKERMANN, OF WILKINSBURG, PENNSYLVANIA, .ASSIGNOR T0 W'ESTIN'GHOIJ'SE'y ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA cATnonnlnAY vApplication led June 22,

My invention relates to cathode-ray oscillographs and particularly to apparatusA for moving the electron beam of an oscillograph of the aforesaid type along a time axis.

In order to -obtain a voltage-time record with a cathode-ray oscillograph, either the f recording surface or the electron beam must be moved along a time axis. This moveinentmay be a continuous one independent of the phenomenon to be recorded (as is the case when either a rotating ilm drum or an "oscillatory voltage continuously impressed on the timing plates is employed) or it may be linitiated shortly before, or at the beginning of, the occurrence of the phenomenon to be recorded. In many respects, the second method of obtaining a time movement is superior to the irst. My invention resides in improvements in theapparatus for initiating a timing movement in accordance with the second-named method.

An object of my invention is to provide,

'in apparatus of the above mentioned type,

means for initiating the timing movement. of the electron beam in response? to the occurrence of a surge or other electrical phenomenon to be recorded.

so designed that, when permanently connected to a transmission line, a surge, occurring on the line, will impress the electron 'beam against the recording surface and simultaneously cause a varying voltage of known characteristics to be impressed on the loscillograph timing plates.

rIhe relay structure, which includes two sets of deflecting plates for bending an electron beam around a target positioned therebetween, is described and claimed in U. S. applications S. N. 238,505 and S. N. 296,844 led in the name of E. H. Norinder on Dec'. 8, 1927 and Aug. 1, 1928, respectively, such applications having been assigned to Westinghouse Electric & Manlufacturing Com-A pany.

In practicing my invention, I employ an evacuated vessel containing a pair of electrostatic deecting plates, a target and means for normally projecting a beam of electrons became-BABE 1929. Serial No. 373,043.

is connected between the target and vground so that, until the electron beam is deiiected, the condenser is charged to a constant potential by the flow of electrons or current from the target to ground. rlhe instant that the electron beam is deflected away from the target, the condenser begins to discharge through the resistance unit, and the voltage impressed across the timing plates is decreased at a known rate.

Other features and advantages of my invention will appear from the following description, taken in connection with the accompanying drawing, in which Figyl is a sectional and diagrammatic view of the apparatus and electrical connections employed in one embodiment of my invention;

Fig. 2, is a view, similar to that of Fig. 1, of the apparatusemployed in another embodiment of my invention and of the electrical connections employed therewith;

Fig. 8, is a view, in longitudinal section, taken on line III-III of Fig. 2;

Fig. 4, is a view, in lateral section, taken on line IV-IV of Fig. 2.

Referring to Fig. 1, the apparatus comprises an evacuated glass vessel 1 having n ieans in the upperend thereof for generating a beam of electrons. The electron-beamgenerating means comprises a cathode 2 of the filament type, which is heated by means of a battery 3, and an anode 4 having an aperture therein positioned below the cathode 2 and supported bymeans of a metal rod 5 sealed into the wall of the glass vessel 1. Some suitable source of high direct-current potential 6 is connected between the cathode 2 and the anode 4.

A. metal target 7 is positioned in the lower end of the evacuated vessel 1 in alignment with the cathode 2 and an aperture in the anode 4. A metal screen 8, having an aperture therein, is supported by means of a' metal rod 9 sealed in the side walls of the glass vessel 1, with the aperture directly 1 above the target 7. The screen is preferably grounded.

Electrostatic defiecting plates 10 of metal are supported by means of metal rods 1l sealed in the side Walls of the glass vessel 1 vand are positioned between the anode 4 and the target 7. One deflecting plate 10 is connected to ground. The other deiecting plate 10 is connected to a point on an electrostatic potentiometer 12. The potentiometer 12 comprises a plurality of condensers 13 connected in series between a transmission line 14 and ground.

The target7 is connected to ground through a resistance unit 15 which has the electrostatic timing plates 16 of a cathode-ray oscillagraph (not shown) connected in parallel therewith. Unless the capacity between the timing plates 16 is suiiicient, a condenser 17 is connected in parallel with the resistance unit 15.

In operation, so long as there is only a normal voltage on the transmission line 14, the beam of electrons will be projected from the opening in the anode 4 against the target 7. These electrons will' then be conducted to ground through the resistance unit 15. This flow of electrons or current will maintain a constant potential across the timing plates 16 and across the condenser 17 to keep the condenser and the timing plates (which also act as a condenser) charged to a fixed degree. As soon as a surge or an unusually high Voltage appears on the transmission line 14, the electron beam will be deflected sufficiently by the delecting plates 10 to move the beam off the target 7 and against the screen 8. rIhis interrupts the iiow of electrons through the resistance unit 15, and the capacity units 16 and 17 immediately begin to discharge therethrough, thus lowering the voltage impressed across the timing plates 16. Since the rate of discharge is known, a known timing movement is imparted to the electron beam of the cathode-ray oscillograph.

v Instead of comprising a separate evacuated vessel, as described in connection with Fig. 1, the structure for initiating the timing movement may be combined with the cathode-ray oscillograph itself, as shown in Figs. 2 to 4.-.

Referring to Figs. 2, 3, and 4, the appara-l tus comprises a metal envelope 20, at the lower end of which is supported a metal casing or chamber 21 in which a suitable photographic plate or film 22 may be placed.

The upper end of the envelope 20 is closed by means of a plug 23 having a tube 24 of insulating material, such as glass, secured thereto and projecting axially from said envelope. The upper end of the tube 24 is provided with a cap 25 centrally apertured to permit the passage therethrough of the terminal 26 of a cathode 27. The cathode terminal 26 is enlarged at 28 to completely close the aperture in the cap 25. A suitable sealing compound may be employed to secure the several elements together. Preferably, a cold cathode is employed, but, obviously, a hot cathode may be employed if desired.

An anode 29 is supported at the lower end of the glass tube 24 and is provided with an axial aperture so that the beam of electrons from the cathode to the anode will pass therethrough.

A frame, which is. supported inside the metal envelope 20, consists of four rods 30 supported at their respective ends and at a point intermediate their ends by rings 3l. The rods 30 are preferably of metal in order to make a strong frame but they may be of insulating material.

Metal delectin plates 32 are secured to the rods 30 near t e upper end of the frame. The plates 32 are insulated from the rods 30 and are connected to terminals 33 that lead through insulating bushings in the metal plugs 34 to the outside of the metal tube 20.

Near the middle of the frame and suitably secured thereto and insulated therefrom, other deflecting plates 35 are supported in parallel relation to the upper deflecting plates 32. The left-hand plate of the lower pair of plates 35 is connected to the right-hand plate of the upper pair of plates 32. Like- Wise, the right-hand plate of the lower pair of plates 35 is connected to the left-hand plate of the upper pair of plates 32.

A target or shield 36 is supported between the two sets of deflecting plates. The target 36 comprises a strip of metal 36 eccentrically mounted on a metal plug 37 which is set into the wall of the casing 20. By rotating the plug 37, the target 36 may be positioned directly in the path of the undeflected electron beam. Since the casing 20 is ordinarily grounded, the target should be insulated from the plug 37 and connected to a terminal rod 38 extending through an insulating bushing in the plug 37.

Below the second pair of deiiecting plates 35 is a screen or diaphragm 39 mounton the rods 30. This screen is preferably of metal and need not be insuluated from the supporting rods 30. The screen is provided with a central opening 40, the diameter of which is approximately the same as the width of the target 36. l

A pair of defiecting or timing plates 41 are mounted on the rods 30 below the screen 39 and insulated therefrom. The timing plates 41 are positioned at right angles to the upper deflecting plates 32 and 35, as is well understood in the art, in order to give the electron beam a timing movement transverse to the movement caused by the upper deiect-` ing plates 32 and 35. As is more clearly shown in Fig. 4, the timing plates 41 are mounted on the rods 30 by means of supporting members 42 and are connecting to termil :maeva lnal rods by means of conductors44. It voltage of known'characteristics is impressed I ltential 45 is connected will bev noted that two ofl ythe rods 30 have been bent around the conductors 44.

A suitable source of hi h direct-current potween the cathode 27 andthe anode 29. The two dellecting plates, which are connected together 'by means of the conductor 46, are connected to a point on an electrostatic potentiometer 47 which is connected between a transmission line 48 and ground.` The other two deflecting plates 32 and 35 are connected to ground. The target 36 is connected to ground through a resistance -unit 49 which, preferably, has a -condenser 50 connected in parallel therewith. One timing plate is connected to the upper end vof the resistance unit, while the other timing plate is connectedto ground.

In operation, a negative voltage is 1mpressed upon the cathode 27 which results, 1n an electron beam shooting through the anode 29 vagainst the target 36. The voltage to be measured is then Iimpressed upon the deflecting plates 32 and 35. In the example illustrated, this voltage is a voltage surge which occurs on the transmission line 48, as the result of some chance disturbance, such as a stroke of lightning. The upper pair of de- "iiectilng plates 32 will so deflect the beam that it will pass to one side of the target 36. The beam will then pass between the second air of defiecting plates 35 and be delecte by them in a direction opposite to the first defiection, as' indicated bythe dotted line 51 in Fig.4 2. The deliected beam will then ass throu h the hole inthe shield 39 and tween t e timing plates 41 and be intercepted by the photographic late 22.' The deliecting plates 32 and 35 an the. screen'39 are so ad]usted with respect to each other that the electron,

beam wi l pass through the aperture vin the screen 39 after it is deflected past the target 36, no matter what the angle of deliection may be.

The angle which the deli'ected beam makes with respect to the longitudinal axis of the tube 20 depends upon the value of the voltage impressed upon the deiecting plates 32 and 35.- Therefore, the amount which the beam is deflected, as recorded on the photo-I graphic plate 22,'is a measure of the voltage impressed upon the deflecting plates.

Since a stationary photographic plate is employed, it is necessary to employ the timing plates 41, as is well understood in the art. It will be seen that, as soon as the electron beam is deflected away from the target 36, the iow of current through the resistance unit 49 is interrupted', and the condenser 5()l discharges therethrough, as described in connection with Fig. 1. Consequently when a surge occurs on the transmission line 48 the electron beam isprojected against the photographic upon the timin plates 41. y

. Various modifications may be made in my invention without departin from the spirit and scope *thereof and I esire, therefore, that on y; such limitations shall be placed thereon as are shown by the prior art and are set forth in the appended claims.

I claim as my invention:

1. Electrical apparatus comprising a target, means for generatin a beam of charged `particles and for proJectin said beam against said target, means for eecting said beam, away from said tar et, an impedance unit, means for conducting said charged particles'away from said target through said unit and means responsive to the voltage drop acrosssaid impedance unit for deflecting a beam of charged particles.

2. Electrical apparatus comprising a target, means forvgenerating a beam of charged particles and for pro]ecting said beam against said target, an impedance unit, means for conducting said charged particles away from said target through said unit and a pair of electrostatic deiiecting'plates connected across said impedance un1t.

y3. Electrical apparatus comprisingl a tarfrom said target through said unit and a pair across said resistance unit.

4. Electrical apparatus comprising a tarof electrostatic deiiecting plates connected get, means for generatin a beam of charged particles and for pro]ecting said beam yagainst said target, a resistance unit, means for conducting said charged particles away from said target through said unit and a condenser and a pair of electrostatic deectmg unit. c

: 5. Electrical apparatus comprising atarparticles and for projecting said beam against said target, means for eflectin said beam away from said target, an impe ancel plates connected across s'aid resistance.

l get, means for generating a beam of charged particles and for projecting said beam against said target, means for deiecting said beam away from said target in response to a quantity to be measured, an impedance unit, means for conducting said charged particles away from said target through said unit and means, including a timing element, for measuring said quantity, said timing element being responsive .to the voltage drop acrogss said impedance unit.

7. Electrical apparatus comprising means for generating a beam of electrons, timing means for giving said beam a timing movefrom said target in response to said quantity, means for storing a quantityv of elect 1ical energy during the time said beam is strllring said target, means for dischargingsaid energy at a predetermined rate the instant that said beam is delected from said target and means -for deflecting said beam in accordance with said discharge. v l

9. Electrical apparatus comprising a target, means for generating a beamof. charged particles and for projecting said beam against said target, means for deiiecting sald beam away from said target, means for storing a quantity of electrical energy during the time said beam is striking said target and means 4for discharging said'energy at a predetermined rate the instant that said beam is deflected from said target.

10. Electrical apparatus comprising a target, means for generating a beam of charged particles and for projecting said beam against said target, means for deflecting said beam away from said target, means for storing a quantity of electrical energy during the time said beam is striking said target, means for discharging said energy at a predetermined rate t-he instant that said beam is deflected from said target and a work circuit so connected that it is actuated in accordance with said discharge.

11. Electrical apparatus comprising a target, means for generating a beam of charged particles and for projecting said beam against said target, means for deflecting said beam away from said target, means for storing a quantity of electrical energy during the time said beam is striking said target, means for discharging said energy at a predetermined rate the instant that said beam is delected from said target and means for deflecting a beam of charged particles in accordance with said discharge.

12. Electrical apparatus comprising means for generating a beam of charged particles, a target positioned in the normal path of said particles, means, including an impedance element, for carrying said particles away from said target, a work circuit connected 'in shunt to said im dance element and means for deflecting said beam of electrons away from said target.

13. Electrical a paratus comprising means for generating a beam of charged particles, a target positioned in the normal path of said particles, means, including a resistance unit, for carrying said particles away from said target, a condenser connected in parallel with said resistance unit whereby a parallel cir- `cuit is formed, a work circuit connected across at least a portion of said parallel circuit'y and means or deflecting said beam of charged particles away from said target.

14. Electrical apparatus comprising means for generating a beam of charged particles, a target, means for projecting said beam against said target, means for deflecting said beam away from said target and means for conducting said charged articles away from said target and for delflecting a beam of charged particles in response to said firstnamed deflection.

15. Electrical apparatus comprising a resistance'unit, and electrostatic timing plates, said resistance and plates being connected in parallel, one end of said unit being connected to a target, means for projecting a beam of charged particles against said target and means for deflecting ysaid beam away from said target in response to a quantity to be measured. f

16.- Electrical ap aratus comprising means for generating an e ectron beam, a resistance, means shunted across at least a portion of said resistance for deflecting said electron beam, means for maintaining a continuous flow of current through said resistance and means for interrupting said continuous flow in response to a quantity to be measured.

17. Electrical apparatus comprising means for generating an electron beam, a condenser, a resistance shunted across said condenser, means shunted across at least a portionI of saidV resistance lfor delecting said electron beam, means for maintaining a continuous How of current through said resistance and means for interrupting said continuous low in response to a quantity to be measured.

In testimony whereof, I have hereunto subscribed my name this 17th day of June,

OTTO ACKERMANN. 

